The following is a tabulation of some prior art that presently appears relevant:
U.S. PATENTSPat. No.ISSUE DATEPATENTEE4,619,899October 1986Nikitin, et al.5,114,854May 1992Bertholdt5,877,008March 1999Remenyik, et al.6,592,552 B1 July 2003Schmidt7,855,067 B2 December 2010Sasaki, et al.FOREIGN PATENT DOCUMENTSFOREIGN Doc. NR.10-2005-0023483WO 2009/070474 A1NON-PATENT LITERATURE DOCUMENTShttp://www.eppendorf.com/int/img/na/lit/pdf8301-C110G-07.pdf